Merge pull request #980 from reaperhulk/dsa-sig-serializer

dss_sig_value: Pure python conversion of (r, s) to byte stream

5 files changed, 45 insertions, 5 deletions

diff --git a/dev-requirements.txt b/dev-requirements.txt
index 092b9914..4fff76b5 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -5,6 +5,7 @@ invoke
 iso8601
 pep8-naming
 pretend
+pyasn1
 pytest
 requests
 sphinx
diff --git a/setup.py b/setup.py
index c841911f..4dd9e629 100644
--- a/setup.py
+++ b/setup.py
@@ -44,6 +44,7 @@ requirements = [
 # If you add a new dep here you probably need to add it in the tox.ini as well
 test_requirements = [
     "pytest",
+    "pyasn1",
     "pretend",
     "iso8601",
 ]
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 7a0b9e74..4673b49e 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -27,11 +27,11 @@ from cryptography.exceptions import UnsupportedAlgorithm, _Reasons
 import cryptography_vectors
 
 from .utils import (
-    check_backend_support, check_for_iface, load_cryptrec_vectors,
-    load_fips_dsa_key_pair_vectors, load_fips_dsa_sig_vectors,
-    load_fips_ecdsa_key_pair_vectors, load_fips_ecdsa_signing_vectors,
-    load_hash_vectors, load_nist_vectors, load_pkcs1_vectors,
-    load_rsa_nist_vectors, load_vectors_from_file,
+    check_backend_support, check_for_iface, der_encode_dsa_signature,
+    load_cryptrec_vectors, load_fips_dsa_key_pair_vectors,
+    load_fips_dsa_sig_vectors, load_fips_ecdsa_key_pair_vectors,
+    load_fips_ecdsa_signing_vectors, load_hash_vectors, load_nist_vectors,
+    load_pkcs1_vectors, load_rsa_nist_vectors, load_vectors_from_file,
     raises_unsupported_algorithm, select_backends
 )
 
@@ -125,6 +125,26 @@ def test_check_backend_support_no_backend():
         check_backend_support(item)
 
 
+def test_der_encode_dsa_signature_values():
+    sig = der_encode_dsa_signature(1, 1)
+    assert sig == b"0\x06\x02\x01\x01\x02\x01\x01"
+
+    sig2 = der_encode_dsa_signature(
+        1037234182290683143945502320610861668562885151617,
+        559776156650501990899426031439030258256861634312
+    )
+    assert sig2 == (
+        b'0-\x02\x15\x00\xb5\xaf0xg\xfb\x8bT9\x00\x13\xccg\x02\r\xdf\x1f,\x0b'
+        b'\x81\x02\x14b\r;"\xabP1D\x0c>5\xea\xb6\xf4\x81)\x8f\x9e\x9f\x08'
+    )
+
+    sig3 = der_encode_dsa_signature(0, 0)
+    assert sig3 == b"0\x06\x02\x01\x00\x02\x01\x00"
+
+    sig4 = der_encode_dsa_signature(-1, 0)
+    assert sig4 == b"0\x06\x02\x01\xFF\x02\x01\x00"
+
+
 def test_load_nist_vectors():
     vector_data = textwrap.dedent("""
     # CAVS 11.1
diff --git a/tests/utils.py b/tests/utils.py
index 60b6f5a2..5c0e2343 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -18,6 +18,9 @@ import collections
 import re
 from contextlib import contextmanager
 
+from pyasn1.codec.der import encoder
+from pyasn1.type import namedtype, univ
+
 import pytest
 
 import six
@@ -80,6 +83,20 @@ def raises_unsupported_algorithm(reason):
     assert exc_info.value._reason is reason
 
 
+class _DSSSigValue(univ.Sequence):
+    componentType = namedtype.NamedTypes(
+        namedtype.NamedType('r', univ.Integer()),
+        namedtype.NamedType('s', univ.Integer())
+    )
+
+
+def der_encode_dsa_signature(r, s):
+    sig = _DSSSigValue()
+    sig.setComponentByName('r', r)
+    sig.setComponentByName('s', s)
+    return encoder.encode(sig)
+
+
 def load_vectors_from_file(filename, loader):
     with cryptography_vectors.open_vector_file(filename) as vector_file:
         return loader(vector_file)
diff --git a/tox.ini b/tox.ini
index da959955..e7d168d6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,6 +7,7 @@ deps =
     coverage
     iso8601
     pretend
+    pyasn1
     pytest
     ./vectors
 commands =